Using the Disk Usage Utility in Offline Mode

If you select the -o option, ibmdu operates in offline mode. The utility assigns default values to the parameters required to make the estimate. In offline mode, ibmdu reads the Lawson dictionary to find the initial and incremental record counts for each table and index listed in the product line's dictionary. From the dictionary, ibmdu reads in the size of a row in each table and index. After it has the record counts and row sizes, it uses the same formulas as bldibmddl to estimate the actual physical size required to hold the extents for Lawson tables.

Keep in mind the following when you use the ibmdu utility in offline mode:

• The accuracy of the ibmdu estimate depends entirely on the accuracy of the row count estimate placed in File Size Definition.

• The row counts in the dictionary are set by the File Size Definition screen in dbdef, followed by blddbdict. You can change these values (as well as tablespaces) and rerun ibmdu without rebuilding the dictionary. To get good estimates, set these values according to the row counts determined by your analysts.

• The estimates are indeed estimates, not exact calculations. You can generally expect them to be off by less than ten percent in either direction, but there are cases where larger margins can be encountered. These cases are indicated by a set of parentheses in the output, and are summarized if you use the warnings (-w) option.

  ibmdu -o[w]bx dataarea [tablespace...]

The ibmdu utility run in offline mode has the following options: